I'm using Scarm, and found it easy to learn. There's a link to my track plan thread in my signature. All of the pictures of the plan, including the 3D ones, are screenshots of Scarm.
I also just installed XTrakCAD and reproduced my plan in it so that I could 'run some trains' on my plan. Scarm will not do that.
I found I could easily accomplish tasks in Scarm, and when I did get stuck I found simple explanations on Scarm's web site in the faq section.
As for XTrakCAD, I found it a little more difficult to learn, but not that much more. It could simply be that I had a number of hours into Scarm when I tried XTrakCAD, and it's a little different. I had to follow a few tutorials on XTrakCAD's web site to learn to do some things with it.